Vacuum cleaner brush roll

ABSTRACT

An autonomous cleaning robot having a body, a driving means configured to move the robot in a forward direction over a surface being cleaned, a suction opening arranged at an underside of the body, and a roller arranged at the underside of the body and in front of the suction opening, relative the forward direction. The roller is configured to define a front air passageway at the surface, and comprises bristles arranged to form a front air barrier restricting an air flow in the front air passageway. The front air barrier is configured to be substantially uniform over an entire turn of the roller, wherein the bristles are further arranged to direct the air flow towards a particle passing by the roller, and further into the suction opening.

TECHNICAL FIELD OF THE INVENTION

The present inventive concept relates to the field of vacuum cleaners,and in particular to autonomous vacuum cleaner robots, and especiallyfor household use.

BACKGROUND OF THE INVENTION

Autonomous vacuum cleaner robots are a type of cleaning devices thatnavigate across a floor surface while removing dirt, such as dust,debris and other particles, from the floor surface. The robot typicallycomprises a chassis provided with wheels and a brush roller that isrotated for the purpose of brushing the dust and particles towards asuction opening, from which the dust and particles are conveyed througha suction channel to an interior of the robot by means of a suctionairflow.

It is desirable to provide an airflow that is sufficiently strong toensure that dust and particles are caught by the flow and transportedinto the suction opening. It is at the same time desirable to provide apower efficient robot, both in term of energy consumption and noiselevel. Thus, a trade-off generally has to be made between dust pick-upand power efficiency.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the present inventive conceptto provide a technology that addresses the above concerns. This andother objects, which will become apparent in the following, areaccomplished by an autonomous cleaning robot as defined in theindependent claim. Preferable embodiments are defined in the dependentclaims.

Thus, according to an aspect, an autonomous cleaning robot is provided,comprising a body, a driving means configured to move the robot in aforward direction over a surface being cleaned, a suction openingarranged at an underside of the body, and a roller arranged at theunderside of the body and in front of the suction opening, relative theforward direction. The roller may be configured to define a front airpassageway at the surface, and comprise bristles arranged to form an airbarrier restricting an air flow in the front air passageway. The airbarrier may be substantially uniform over an entire turn of the roller,and the bristles may be arranged to direct the air flow towards aparticle passing by the roller, and further into the suction opening.

The present inventive concept involves the realisation that it isdesirable to direct as much as possible of the airflow in the front airpassageway towards the surface to be cleaned, since the dust pick-upgenerally tends to increase with increasing flow and/or speed of the airthat passes over the surface. The present inventive concept isassociated with several advantages—firstly, the bristles are arranged toform an air barrier that restricts the airflow in the front airpassageway. This allows for a general reduction in power consumption andnoise, since the fan that generates the suction airflow can operate on areduced power level. Secondly, the bristles are arranged to direct theair flow towards a particle passing by the roller. This may for examplebe achieved by the bristles being bent or pushed aside by the particleas the roller passes over the particle, such that a gap or passage isformed in the barrier, allowing for a local flow passageway to be formedat the location of the particle, through which the airflow may beconcentrated and passing with a relatively high speed that facilitatestransport of the particle towards an interior of the robot.

The bristles may be arranged to form an air barrier that issubstantially uniform over an entire turn of the roller. This may forexample be achieved by distributing the bristles uniformly over theenvelope surface of the roller, or at least such that the number ofbristles pointing towards the surface is substantially constant duringthe entire turn of the roller. A uniform barrier allows for theperformance of the robot, and the suction conditions under which itoperates, to be constant while the roller is rotated. Advantageously,this allows for a smooth operation and reduced noise—especially comparedto prior art rollers comprising bristle rows and/or rubber vanes thattend to whip the surface during the rotation.

A consequence of increasing the distribution density of the bristles,i.e., the number of bristles per unit area, is that the roller may beoperated at a reduced speed while maintaining the same number ofbristles passing the surface for a given time period. This allows for areduced power consumption and noise level.

By “air barrier”, which also may be referred to as a “sealing”, is meanta feature that prevents a substantial amount of air from passing towardsthe suction channel, but does not require an air tight seal. The airbarrier may be characterised by the flow resistance in the airpassageway through which the air passes on its way to the suctionchannel. The flow resistance may, in turn, be defined by the density bywhich the bristles are arranged on the roller, the length of thebristles, and any gap between the bristles and the surface to becleaned. Increasing the density of the bristles, i.e., the number ofbristles per unit area of a core of the roller, may increase the flowresistance experienced by air passing between the bristles. Further,reducing the length of the bristles may result in a narrower passagewayand hence an increased flow resistance, while introducing a gap betweenthe roller and for example the surface to be cleaned may reduce the flowresistance. Thus, it is desirable to use a larger number of shorterbristles that are arranged to engage the surface such that no additionalgap is formed that may impair the barrier function of the roller. Theterm “restricting an airflow” therefore refers to the bristle'scapability of forming an air barrier, or seal, with an adjacent surface,such as the floor surface, during operation of the robot—preferably byengaging the surface such that most of the air passing through the frontair passageway has to pass through the roller, i.e., between thebristles.

By the bristles being arranged to “direct the airflow towards aparticle” is understood a capability to focus at least some of theairflow in the front air passageway towards the particle. A particle mayinteract with the roller in several ways depending, inter alia, on thesize of the particle in relation to the spacing and length of thebristles. Preferably, the particle is sufficiently large, relative thelength of the bristles and the spacing of neighbouring bristles, to pushor bend them away from each other, thereby forming a local passageway inwhich an airflow may be passed to entrap the particle. Further, theparticle is sufficiently small to fit in the front air passageway, i.e.,to be pushed into the bristles and further towards the suction opening.Generally, this requires the particle to be of a size that does notexceed the length of the bristles and/or the spacing between a core ofthe roller and the floor surface.

A device as described in the context of the present disclosure is oftenreferred to as an autonomous cleaning robot due to the fact that thedevice can automatically move around on a work surface according to, forexample, a predetermined or randomised pattern. The device may generallybe used to clean the surface from dust, debris, gravel, sand, hair, andother particles.

As already mentioned, the bristles may be arranged in a non-uniformmanner over an envelope surface of the roller. The bristles may forexample be arranged to cover only a part of a length portion facing thesurface as the roller is rotated. Preferably, the bristles are arrangedto form an air barrier that extends along a substantial part of thelength portion facing the surface. Thus, according to an embodiment, thebristles may be distributed such that the number of bristles pointingtowards the surface are distributed over a length portion of the rollerthat corresponds to at least 50%, such as at least 75%, of a totallength of the roller so as to provide an increased sealing and lessnoise.

Alternatively, the bristles may be uniformly distributed over the entireenvelope surface of the roller or substantially the entire envelopesurface of the roller.

The bristles, which may be formed as short hairs or whiskers, may befastened to a core of the roller such that they stand substantiallyupright from the surface of the core, pointing in a radial direction ofthe roller. Preferably, the bristles have a length of 3-15 mm, such as3-10 mm or 3-7 mm. In a specific example, the bristles may have a lengthof 5.5 mm. Further, the bristles may be arranged with a density of 1000-20 000 bristles per cm², such as 10 000-18 000 or 12 000-17 000 percm². In two specific examples, the bristles may have a density of 2 000per cm² (for harder brush rolls) and 13 200 per cm² (for softer brushrolls), or a mix of lower and higher density bristles. The bristles mayfurther have a diameter of 0.03-0.15 mm, such as for example 0.05 mm. Insome examples, the core (i.e. the roller without the bristles) may havea diameter in the interval of 8-40 mm, such as for example 15-25 mm.

According to an embodiment, the robot may further comprise a sealingedge arranged behind the suction opening, relative the forwarddirection. The sealing edge may be arranged spaced from the surface todefine a rear air passageway between the surface and the sealing edge.Thus, the air that is sucked into the robot and forms the suction airflow may take at least two different ways—either the front airpassageway through the roller, or the rear air passageway behind theroller. Preferably, the flow resistance is higher in the rear airpassageway than in the front air passageway to force the air to passthrough the front air passageway and thereby increase dust-pickup. Thismay be achieved by reducing the clearance between the sealing edge andthe surface to be cleaned. In case the robot is operating mainly duringits forward motion, the clearance between the sealing edge and thesurface may be even further reduced.

According to an embodiment, the robot may further comprise a rollerhousing with an inner surface that is arranged to partly surround theroller, along a portion of the roller facing away from the surface beingcleaned, to form an upper air passageway with the roller. Thus, the airthat is sucked into the robot may take at least three different ways,i.e., the front air passageway, the rear air passageway, and the upperair passageway. Preferably, the flow resistance in the upper airpassageway is higher than in the front air passageway so as to forcemost of the air to pass through the latter. This may be accomplished byreducing a distance between the inner surface and the roller, andfurther by increasing the length of the upper air passageway byincreasing the circumferential distance of the roller over which theinner surface extends.

According to an embodiment, the roller is rotatable such that a portionof its envelope surface facing the surface to be cleaned is movedtowards the suction opening. Put differently, the roller may berotatable in the same direction as the rotation of the wheels of therobot when the robot is moving in the forward direction. Preferably, theroller is rotated at a speed allowing it to brush dust and particlestowards the suction opening, rather than merely rolling over them.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as additional objects, features and advantages of thepresent inventive concept, will be better understood through thefollowing illustrative and non-limiting detailed description ofembodiments. Reference will be made to the appended drawings, on which:

FIG. 1 illustrates a top view of an autonomous cleaning robot accordingto an embodiment;

FIG. 2 is a cross section of an autonomous cleaning robot according toan embodiment;

FIG. 3 is a cross section of a roller of an autonomous cleaning robotaccording to an embodiment; and

FIG. 4 is a perspective view of a roller of an autonomous cleaning robotaccording to an embodiment.

Like reference numerals are used for like elements on the drawings.Unless otherwise indicated, the drawings are schematic and generally notto scale.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 is a top view of an autonomous cleaning robot 100 for householduse according to an embodiment, comprising a body 110, a driving means120, 121, a suction opening (not shown), a suction unit 112 and a roller140. The body 110 may form a chassis having an outer cover forprotecting and enclosing functional units, such as control electronics,dust box and fan unit, arranged in the interior of the robot. Further,the chassis may provide support for the driving means 120, which in thepresent example is represented by two driving wheels 120 and a supportwheel 121 arranged at the underside of the chassis. The driving of thedrive wheels 120 may be performed by separate motors for improvednavigation and movement control.

The roller 140 may be arranged at the underside of the chassis, and suchthat it engages a surface of the floor during operation. Preferably, theroller 140 is arranged in the front third of the body, as seen in theforward direction. The roller 140 may comprise a core and a plurality ofbristles, which will be described in more detail in connection with thefollowing figures.

During operation, the robot 100 may move autonomously over the surfaceto be cleaned, and preferably in a forward direction indicated by thearrows in FIGS. 1 and 2. When moving in the forward direction, debris,dust and other particles may be engaged by the bristles of the roller140 and sucked into the interior of the robot 100 by means of an airflowthat is passing over the surface. The roller 140 may preferably rotatein the same direction as the wheels 120, and with a speed that allowsthe bristles to brush the particles towards the suction opening 132 inthe body 110 of the robot 100.

FIG. 2 is a cross section of a cleaning robot 100 according to anembodiment, which may be similarly configured as the cleaning robotdiscussed in connection with FIG. 1. Thus, the robot 100 may comprise abody, or chassis 110, accommodating a suction unit 112 for generating asuction airflow and filtering out dust and particles from the same. Thesuction airflow passes through the suction opening 132 and into thesuction channel 130, leading into the interior of the robot 100. Thesuction opening 132 may be arranged at least slightly behind the roller140 as seen in the forward travel direction indicated by the arrow.

In connection with the suction opening 132, and at the underside of thechassis 110, the roller 140 may be arranged for facilitating transportof dust and particles into the suction channel 130. The roller 140 maycomprise an air impermeable core 144, which may be substantiallycylindrical, onto which a plurality of bristles 142 may be attached. Thebristles 142 may be attached with one end to the core such that theother end points away from the core 144, along a radial direction of theroller 140. The bristles may be arranged to form an air barrier thatrestricts the air flow in a front air passageway F between the core 144and the surface. Preferably, the roller 140 is arranged to engage thefloor surface during operation, such that the air in the front airpassageway passes through the bristles 142 on its way towards thesuction channel 130. By arranging the bristles 142 sufficiently dense interms of number of bristles per unit area, a sealing against the surfacemay be accomplished that prevents a substantial amount of air frompassing through the front air passageway F.

The chassis 110 may further comprise a sealing edge 150 arranged at theunderside of the chassis 110 and behind the suction opening 132,relative the forward direction. The sealing edge 150 may be provided toreduce a clearance between the chassis 110 and the surface and therebydefine a rear air passageway R for the air entering the suction opening132 and passing towards the suction channel 130. Preferably, theclearance between the chassis 110 and the surface is smaller behind theroller 140 than in front of the roller 140, to provide a flow resistancein the rear air passageway R that is higher than in the front airpassageway F. The clearance behind the roller 140 may for example be 0-7mm. In an example, the sealing edge 150 is arranged to abut the surfaceto provide a flow resistance in the rear air passageway R that is higherthan in the front air passageway F and hence force most of the airpassing into the interior of the robot 100 to pass through the front airpassageway F rather than the rear air passageway R.

A further air passageway may be defined at the upper side of the roller140. This air passageway may hence be referred to as an upper airpassageway U, and may be defined between an inner surface of a rollerhousing 160. The flow resistance along the upper air passageway U may beincreased by increasing the length of the passageway and/or reducing aspacing between the inner surface and the roller 140. It is advantageousto use an upper air passageway that has a higher flow resistance thanthe front air passageway F, which allows it to restrict most of theairflow to the front air passageway F and thereby force the flowing airtowards the surface to be cleaned.

FIG. 3 is a cross section of a roller according to an embodiment, whichmay be similarly configured as the embodiments discussed above inconnection with FIGS. 1 and 2. The roller 140 may comprise asubstantially cylindrical core 144 that can be mounted in the chassissuch that it is rotatable around its length axis A, and spaced apartfrom the floor surface during operation. Further, the roller 140comprises a plurality of bristles 142 arranged in a protruding manner onthe air impermeable core 144. The bristles may be distributed such thatthe number of bristles that for a given point in time are directedtowards the surface is constant. Further, as illustrated in the presentfigure, the bristles 142 may be evenly distributed along the length axisA of the core 144 such that the number of bristles pointing towards thesurface are distributed along the entire length of the roller 140. Inthe present example, the bristles may be formed of nylon, polypropyleneor hair.

The bristles 142 may be arranged such that they give way for a particleP passing under the roller 140. More specifically, the bristles 142 maybe bent or pushed aside by the particle P such that an opening is formedin the barrier, allowing a flow of air to be directed towards theparticle P and further into the suction opening. As indicated in thepresent figure, the particle P is small enough to pass through the gapdefined by the clearance between the core 144 and the surface, and largeenough to bend the bristles 142 to the side to create a local airflowthrough the barrier.

FIG. 4 is a perspective view of a roller 140 according to an embodiment,which may be similar to the embodiments described with reference toFIGS. 1 to 3. In the present example, the bristles 142 are distributedsubstantially uniformly over the entire roller 140, with the exceptionof one or several helical regions 146 wound around the length axis A ofthe roller 140. The helical region 146 forms a local gap in the airbarrier, which due to the helical arrangement moves along the lengthaxis A as the roller 140 rotates. The gap may for example be provided inorder to provide a slight increase in the air flow through the front airchannel. It may be desired to increase the air flow depending on thecharacteristics of the surface and to reduce the friction generatingvacuum between the robot and surface.

The person skilled in the art is by no means limited to the exampleembodiments described above. On the contrary, many modifications andvariations are possible within the scope of the appended claims.Additionally, variations to the disclosed examples can be understood andeffected by the skilled person in practising the claimed inventiveconcept, from the study of the drawings, the disclosure, and theappended claims. The mere fact that certain measures are recited inmutually different dependent claims does not indicate that a combinationof these measures cannot be used to advantage.

1. An autonomous cleaning robot, comprising: a body; a driving meansconfigured to move the robot in a forward direction over a surface beingcleaned; a suction opening arranged at an underside of the body; and aroller arranged at the underside of the body and in front of the suctionopening, relative the forward direction; wherein: the roller isconfigured to define a front air passageway at the surface beingcleaned; and the roller comprises bristles arranged to form a front airbarrier restricting an air flow in the front air passageway, the frontair barrier being configured to be substantially uniform over an entireturn of the roller, wherein the bristles are further arranged to directthe air flow towards a particle passing by the roller, and further intothe suction opening.
 2. The autonomous cleaning robot according to claim1, wherein the bristles are distributed such that the number of bristlespointing towards the surface are distributed over a length portion ofthe roller corresponding to at least 50% of a total length of theroller.
 3. The autonomous cleaning robot according to claim 1, whereinthe bristles are uniformly distributed over substantially an entireenvelope surface of the roller.
 4. The autonomous cleaning robotaccording to claim 1, wherein the bristles are arranged with a densityof 1 000-20 000 bristles per cm².
 5. The autonomous cleaning robotaccording to claim 1, further comprising a sealing edge arranged behindthe suction opening, relative the forward direction, and configured tobe spaced from the surface so as to define a rear air passageway betweenthe surface and the sealing edge.
 6. The autonomous cleaning robotaccording to claim 5, wherein the sealing edge is arranged such that aflow resistance of the rear air passageway is higher than a flowresistance of the front air passageway.
 7. The autonomous cleaning robotaccording to claim 5, wherein a clearance between the surface and thesealing edge is smaller than, or equal to, a clearance between thesurface and the body in front of the suction opening, relative theforward direction.
 8. The autonomous cleaning robot according to claim7, wherein the clearance between the sealing edge and the surface is 0-7mm.
 9. The autonomous cleaning robot according to claim 1, furthercomprising a roller housing having an inner surface, wherein the innersurface is arranged to partly surround the roller, along a portion ofthe roller facing away from the surface being cleaned, to form an upperair passageway with the roller, the upper air passageway having a higherflow resistance than the front air passageway.
 10. The autonomouscleaning robot according to claim 1, wherein the roller is rotatablesuch that a portion of its envelope surface facing the surface to becleaned is moved towards the suction opening.
 11. The autonomouscleaning robot according to claim 1, wherein: the bristles protrude froma surface of a core of the roller, the core has a diameter in the rangeof 8-40 mm, and the bristles have a length in the range of 3-15 mm. 12.The autonomous cleaning robot according to claim 1, wherein the rolleris arranged in the front third of the body, as seen in the forwarddirection.
 13. (canceled)
 14. The autonomous cleaning robot according toclaim 11, wherein the core has a diameter in the range of 15-25 mm. 15.The autonomous cleaning robot according to claim 11, wherein thebristles have a length in the range of 3-10 mm.
 16. The autonomouscleaning robot according to claim 11, wherein the bristles have a lengthin the range of 3-7 mm.
 17. The autonomous cleaning robot according toclaim 1, wherein the bristles are arranged with a density of 10 000-18000 bristles per cm².
 18. The autonomous cleaning robot according toclaim 1, wherein the bristles are arranged with a density of 12 000-17000 bristles per cm².